Rotary engines which include a housing formed with a cylindrical shaped chamber in which one or more pairs of pistons are located are well known. The pistons are interconnected for rotation at relatively periodically variable speeds whereby piston chambers of periodically variable volume are formed between adjacent piston faces. Engines of this type are shown, for example, in U.S. Pat. Nos. 4,646,694 - Fawcett; 3,396,632 -Leblanc; 3,256,866 - Bauer; and 2,804,059 -Honjyo. Rotary engines of this type are limited in the amount of expansion of the burning fuel which may take place before the exhaust phase of the cycle takes place.
In order to extend the expansion phase, the use of compound engines which include interconnected first and second engine sections has been suggested. Ignited combustibles from a first, or primary, engine section are supplied to a second, or secondary, engine section where they are combined with additional air to support burning of leftover combustibles. Exhaust products are exhausted from the secondary engine section. A compound engine employing such primary and secondary rotary engine sections is shown in U.S. Pat. No. 4,086,882 - McCrum. Superchargers for compressing air supplied to engines of either the Otto or Diesel type are well known as shown, for example, in Van Nostrand's Scientific Encyclopedia - 4th Edition - D. Van Nostrand Company, Inc. 1968 - pp. 1773-1775.
The work output of many rotary engines is limited by the limited amount of expansion of the burning fuel/air mixture which is possible during the power phase of the operating cycle before the exhaust phase is initiated. Also, sealing of the pistons in the cylindrical chamber is difficult with many prior art rotary engines.